This is an anglicized form of the Olde Irish name O'Tegan or O'Teegan, and originally found in the counties of Kildare and Leix. The sept were originally quite numerous to the extent that the village of Ballyteegan is named after them. The 1845-46 Famine was responsible for many of the names emigrating and the corruption in spelling. It is however possible that some name holders may have a Dutch origin and derive from Tegelin or Tegeln a name recorded in the City of Cleves C. 1680 The first recorded spelling of the family name is shown to be that of O'Tadhgain (the descendant of the son of Tadhg) which was dated 1654 The All Ireland Census during the reign of Richard Cromwell The Lord Protector 1658-59 Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.